Effects of coated and incorporated N-(n-butyl) thiophosphoric triamide urea-nitrogen dynamics in soils on growth and yield of maize (Zea mays L. var. thai super sweet)
Urea fertilizer is the most convenient nitrogen (N) fertilizer commonly being applied to soils for crop production due to its high N percentage (46%). Nonetheless, N in urea could be lost due to rapid hydrolysis which resulted in increased N loss through ammonia volatilization, leaching and de...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2020
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/99424/1/FP%202021%2039%20UPMIR.pdf |
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| Summary: | Urea fertilizer is the most convenient nitrogen (N) fertilizer commonly being
applied to soils for crop production due to its high N percentage (46%).
Nonetheless, N in urea could be lost due to rapid hydrolysis which resulted in
increased N loss through ammonia volatilization, leaching and denitrification.
Currently, urea fertilizer treated with N-(n-butyl) thiophosphoric triamide (NBPT)
has been developed to overcome loss of nitrogen from urea by inhibiting the
urease activity which slow down urea hydrolysis. However, the effectiveness of
urea treated with NBPT on crops in Malaysian highly weathered soils are not
known. Thus, this research was undertaken to study N transformation and
volatilization from NBPT treated urea fertilizer comprising of NBPT coated urea
(NCU) and NBPT incorporated urea (NIU) in selected Malaysian soils, as well
as to determine their effects on nitrogen use efficiency (NUE), N uptake and
growth of maize under field conditions. Laboratory trials were conducted to
study N mineralization, volatilization and soil leaching from three types of
fertilizers (NCU, NIU and urea) in three different soil series (Morib, Bungor and
Serdang). Results indicated after 7 days of incubation, all NCU and NIU treated
soils showed significantly (P≤0.05) higher total inorganic N and reduced NH3
volatilization by 45.13% - 53.27% compared to untreated urea. The resulted on
soil leaching showed that NBPT treated urea had higher ammonium content
compared to urea during 3rd – 4
th pore volume. With regards to soil series,
Bungor was found to have more inorganic N and reduced NH3 losses than
Serdang and Morib. It showed that NCU and NIU had capability to reduce
ammonia volatilization losses in all three different soil series. For the first field
study, maize plant were subjected to six treatments: two of which were
controls, T0 = unfertilized and T1 = 120 kg N ha-1 of urea, and four NCU
treatments at 144 kg N ha-1
(T2), 120 kg N ha-1
(T3), 96 kg N ha-1
(T4) and 72
kg N ha-1
(T5). Plant growth, yield, N uptake, NUE and soil inorganic N were
measured at v6 (32 DAP), v10 (53 DAP), VT (60 DAP) and harvesting time (79 DAP). Relatively, NCU at 120 kg N ha-1 and 96 kg N ha-1 were effective in
increasing growth, yield, N uptake and NUE. Improvement of NUE by 45% over
urea was recorded in the treatment of NCU at 96 kg N ha-1
. This showed that
almost 20% of fertilizer usage could be saved rather than the usual 120 kg N
ha-1
. While in second field study, T1 (control) and best 3 NCU treatments (T3,
T4 and T5) from first field study were selected and further tested and compared
to NIU at similar rate as T3, T4 and T5. Growth data were measured 1 week
after basal fertilization (21 DAP), 1 week after side dressing (49 DAP) and
harvesting time (75 DAP) which included plant growth, yield and N uptake.
Results demonstrated that NCU and NIU treatments at 120 kg N ha-1 and 96 kg
N ha-1 significantly (P≤0.05) increased maize growth and yield compared to
untreated urea. Also, our findings exhibited no significant difference (P>0.05)
between NCU and NIU at 120 kg N ha-1 and 96 kg N ha-1
. Thus, NIU at 96 kg N
ha-1 was recommended as it could prolonged more storage time compared to
NCU. This study provided evidences that NBPT can reduce N loss, thus
ensuring more N for longer period in soils, enabling more N available for plant
N uptake, hence promote growth and yield for grain crop in highly weathered soils. |
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